Might have gone off by accident.
indeed, let's look at the positives here too. if this was some kind of planned terror attack - it failed.
Or planted by another party.
IMHO, insufficient evidence, but good basis for investigators to publically announce it as an isolated event, while rigorously investigating all angles of this in the background.
Many campus' are fairly vacant in the Sci/engr buildings during ball games or other social events. A handful of grad students working aren't conspicuous. Prime time for either an alienated individual to become overly depressed and seek a suicide opportunity unimpeded by outsiders, or other ulterior motives.
On the other hand it might also be a good time to use, misuse, or intrude into facilities with minimal risk.
Insufficient information,..the rest is merely conjecture, bits and pieces (no pun intended).